How to show a hologram in free space?

One of the questions in holoferencing is how to show a hologram in free space. Awareness of a person in our proximity is caused by a stimulus of our senses. The five senses we use are hearing, seeing, feeling, smelling an tasting. For holoferencing it would be fine if we could make hearing and seeing work. But lets focus on seeing in this post.

Seeing an object in free space is basically caused by reflection of light on a surface entering our eyes. So the question could be how we can imitate the reflection of light in a free space? Can we emulate the reflection of light of a specific color in free space, with only air in it. This could be by making something reflect the available light or be a source of light as if it was reflected by a colored surface. We will need to think 'out of  the box' on this challenge.

What if we could manipulate air in a way that would make it reflect light? Or how can we make two or three different sources (of a kind) causing light at the intersection point of those three sources? Or can we fill the room with (harmless) matter that would react on the intersection of some kind of waves with the radiation of light?

If this is possible we can eliminate the need for screens and 3D glasses to have this holograms of other people moving around the room and we ourselves being able to move around the hologram without interrupting its presence.

Is there any research going on with respect to this subject?

Microsoft working on teleconferencing

They call it Viewport. Some time ago Microsoft published a white paper about this new product intended to provide “a videoconferencing experience that creates the illusion that the remote participants are in the same room with you”, This does sound familiar. See my first blog on this subject dated May 2006. Shortly after my first blog Wainhouse Research produced a segment report on this subject. Did I inspire some readers of that blog to investigate and start research on this subject?

It is clear that holoferencing is not a forgotten subject. Some progress is made on the development of the required technology and prerequisites became viable or available in the mean time. So what will it take to experience the first real implementations of holoferencing? Unfortunately 'Scotty' will not experience the first edition of this new frontier 'where no man has gone before'. But will we live to see it?